## Facts

- The claimant’s husband was employed as a galvaniser by the defendant company.
- During the course of his employment, he suffered a burn to his lip from molten metal due to inadequate safety measures implemented by the employer.
- The burn activated an existing pre-cancerous condition, accelerating the onset of cancer that resulted in the employee’s death three years later.
- The claimant, as the widow, brought a negligence claim against the employer, arguing liability for the death, notwithstanding the pre-existing vulnerability.
- The court was asked to determine whether the employer’s responsibility extended to consequences made worse by the employee’s unique pre-existing condition.

## Issues

1. Whether a defendant is liable for unforeseeable extent of harm caused by a negligence act when the claimant has a pre-existing vulnerability.
2. Whether foreseeability in negligence applies to the type of harm or also the extent of the injury sustained.
3. Whether the defendant could avoid or limit liability because the victim’s personal condition exacerbated the injury.

## Decision

- The court held the employer liable for the full extent of harm, including death from cancer accelerated by the initial burn.
- It was determined that, although the cancer was an unexpected consequence, the burn was a foreseeable type of injury.
- The defendant was found responsible for all consequences arising from their negligent act, regardless of the victim’s particular susceptibility.
- The Wagon Mound principle regarding foreseeability of type of damage was held compatible with the ongoing application of the thin skull rule.

## Legal Principles

- The “thin skull rule” (or “eggshell skull rule”) requires a tortfeasor to take the victim as found, including any pre-existing vulnerabilities.
- Liability in negligence is assessed based on foreseeability of the type, not the extent, of harm.
- The “but-for” causation test applies: the defendant is liable if the harm would not have occurred but for their negligence.
- The principle covers both physical and psychological vulnerabilities.
- The foreseeability required is of the category of harm, not of the magnitude, as confirmed by references to The Wagon Mound.

## Conclusion

Smith v Leech Brain & Co Ltd confirmed that defendants are fully liable for all harm caused by their negligence, even when a claimant’s pre-existing condition leads to unusually severe consequences. The case established the lasting authority of the thin skull rule in English tort law, clarifying that foreseeability applies solely to the type of harm, not its extent, and that liability cannot be reduced because the claimant was particularly vulnerable.


Smith v Leech Brain & Co Ltd [1962] 2 QB 405